The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
Does Lack of Sleep Cause Weight Loss or Gain?
Poor sleep doesn't typically cause weight loss — in fact, lack of sleep most commonly leads to weight gain. When you don't get enough sleep, your body's hunger-regulating hormones become imbalanced, increasing cravings for high-calorie foods and reducing your motivation to exercise. Sleep deprivation also slows metabolism and affects how your body stores fat. If you're struggling with weight management alongside poor sleep, talk to your GP about lifestyle changes or prescription weight loss options available in the UK.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
How Sleep Deprivation Affects Weight
Lack of sleep disrupts the hormones that control appetite and weight. When you sleep poorly, your body produces less leptin (the hormone that signals fullness) and more ghrelin (the hormone that triggers hunger). This combination makes you feel hungrier, particularly for sugary and high-fat foods.
- Sleep deprivation reduces metabolic rate, meaning your body burns fewer calories at rest
- Poor sleep impairs decision-making around food choices, making unhealthy options more tempting
- Fatigue reduces motivation for physical activity, leading to fewer calories burned
- Sleep loss increases cortisol (stress hormone), which promotes fat storage around the abdomen
Research shows that people sleeping fewer than 7 hours per night are significantly more likely to gain weight than those sleeping 7–9 hours. If you're experiencing both poor sleep and weight gain, addressing sleep quality is an important first step. Try our free BMI calculator to check your current weight status, and use our weight converter to track your measurements across kg, stone, and lbs.
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Weight Management Options in the UK
If lifestyle changes alone aren't helping, prescription weight loss medication is available through the NHS or privately in the UK. Adults with a BMI of 30 or above, or 27 or above with weight-related health conditions, may be eligible for treatment.
- Mounjaro (tirzepatide) — once-weekly injection that may help reduce appetite and support weight loss
- Wegovy (semaglutide) — GLP-1 injection available in the UK for eligible adults
- Saxenda (liraglutide) — daily injection option for weight management
NHS access is through specialist tier 3 weight management services, though availability varies by region. Private prescription options are also available following an online clinical assessment. Try our GLP-1 weight loss calculator to explore potential outcomes, and speak with your GP about whether prescription options are right for you.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Does lack of sleep directly cause weight gain?
Not directly, but sleep deprivation significantly increases the likelihood of weight gain. Poor sleep disrupts hormones that regulate hunger and metabolism, making weight gain more probable. Most people gain weight when sleep-deprived because they eat more and move less, not because sleep loss burns fewer calories directly.
How much sleep do I need to maintain a healthy weight?
The NHS recommends 7–9 hours of quality sleep per night for adults. Studies show that sleeping fewer than 7 hours is associated with increased weight gain risk. Improving sleep quality is an evidence-based part of sustainable weight management alongside diet and activity.
Can I lose weight while sleep-deprived?
It's much harder to lose weight on insufficient sleep. While a calorie deficit is still the primary driver of weight loss, poor sleep increases hunger hormones, reduces motivation for exercise, and impairs food decision-making. For best results, aim to improve both sleep and nutrition simultaneously.
What's the link between insomnia and weight?
Chronic insomnia disrupts the same hunger-regulating hormones affected by acute sleep loss. People with long-term sleep problems often experience sustained weight gain over time. If you have insomnia, speak to your GP about sleep support alongside weight management strategies.
Are weight loss injections available on the NHS if I'm overweight?
Prescription weight loss medications like Mounjaro and Wegovy are available through NHS specialist tier 3 weight management services for eligible adults (BMI ≥30, or ≥27 with health conditions). Access varies by region. Your GP can assess eligibility and refer you to local specialist services, or private options are available through online clinical assessment.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.